Using RVM

1. Install RVM
2. Add the snipped to ~/.bash_aliases. The RVM install script may report a different path--use that one.

   if [[ -f $HOME/.rvm/scripts/rvm ]]; then
       source $HOME/.rvm/scripts/rvm
   fi
   

3. rvm install 3.0.0, or any other ruby version
4. rvm --default use 3.0.0, or the installed version
5. Check the output of which gem. It should point to the installed one.
6. gem install bundler
7. bundle install to install the gems needed for a project
8. bundle exec jekyll serve